CLEVELAND HEIGHTS, Ohio - About 4,000 customers in Cleveland Heights, University Heights and Cleveland's East Side remained without electrical power Thursday as First Energy repair crews continued to work toward restoring service in the wake of Tuesday's thunderstorms.

First Energy hoped to restore power to all customers by midnight Thursday, said spokesman Mark Durbin, but he acknowledged that some customers probably won't have power back until Friday.

Severe thunderstorms Tuesday that toppled utility poles and trees and downed limbs knocked out power for about 45,000 customers, Durbin said.

The greatest damage was caused by thunderstorm microbursts -- localized channels of air that speed downward from the base of a thunderstorm which can cause isolated damage while leaving surrounding areas undisturbed. According to the National Weather Service, the microburst that hit Cleveland Heights, generated 80 mph winds.

Why is it taking so long?

Work has been slowed, in some cases, because electrical service in many of the neighborhoods is at the back of the residential lots, rather than along the street.

"The problem with that is you can't get a bucket truck back in there," Durbin said. "Those areas are beautiful with all those gorgeous trees, but when [the trees] are on the ground, and on their way down to the ground they take out lines, it just complicates the process."

In those neighborhoods, Durbin said, workers have to work on the lines the old fashioned way - climbing the pole with spikes on their shoes, often lugging as much as 40 pounds of gear.

How bad is the problem still?

By Thursday the outage totals had been whittled down to about 4,000, mostly in Cleveland Heights, University Heights and in some neighborhoods on Cleveland's East Side. Durbin estimated about 2,600 were in Cleveland Heights.

One business hit hard by the storm was Zagara's Marketplace, a grocery store on Lee Road in Cleveland Heights. The store lost power for about 21 hours initially. On Thursday morning the power went down again for a brief period.

The result was that thousands of dollars worth of food -- much of the store's refrigerated products -- had to be discarded because of food safety regulations.

"What could be put away before it was too late was put away, but a lot of things just had to sit in the cases," said Mary-Grace (Zagara) Healy. "We threw out ... two dumpsters worth of merchandise, unfortunately."

On Thursday the store had little to no food in its dairy, meat, seafood and deli cases.

"To see that much food being thrown out, it just breaks your heart," Healy said.